The Natural Science Education Trail along the celebrated cold Hubelj River is 3,100 meters long and includes 24 information points where we learn about individual tree species, the bedrock, the soil, the water ecosystem, and the animals.
The Hubelj River flows from below Mount Šturska gora, shapes limestone rocks, and collects its water in the rocky dark underground of three caves: Velika hubeljska kuhinja, Pajkova reža, and Vzhodna hubeljska jama. The water calms down in pools, rushes across cascades, and makes its way through the lush greenery in its lower course. The water of the Hubelj River is cold (7–8 degrees Celsius), rich in minerals, and ranks among the best drinking waters.
Among the vegetation along the river, see wild cherry, dogwood, black alder, black pine . . . Škol, an ecosystem of karst meadow with sumac, dog rose, and black alder, is interesting as well.
In the water, we can find bullhead, marble trout, rainbow trout, eels ... Among water birds, let us mention the dipper, the kingfisher, the grey heron . . .